Graves Q mana cost.

Graves Q at rank 5 says it costs 70 mana, and shows so when mana costs are displayed. http://imgur.com/F9NOgQy However, as seen, I cannot cast it, it is only till I have 100 mana, that I can cast the ability. http://imgur.com/97K17vw This is false according to both the cost on the ability, and the cost in the description. http://imgur.com/NuFr8QP Thanks for checking it out and clarifying the mana cost. This is on OCE, I dont know if it is similar affects on the other ranks.